Multiple master typefaces have been used since the early 1980's when they were introduced in Germany in a computerized typeface generation system called "Ikarus". These typefaces were also described in U.S. Pat. No. 4,933,866 which issued on Jun. 12, 1990, and is incorporated herein by reference.
As a simple example of multiple master typefaces, consider a typeface with a design matrix based on a single variable--weight. This weight variable varies along a weight design axis. At one end of the axis is the master design of least weight, called "light"; at the other end the design of heaviest weight, called bold. An example using the character "W" is shown in FIG. 1. The user can select a custom weight value virtually anywhere along the weight design axis 13.
More complex matrices are also possible using more than one design axis, for example weight and width. A user can generate an instance of a character on-the-fly by choosing a point anywhere along the two design axes of such a multiple master typeface.
Prior to the development of multiple master fonts, a font family included only several discrete weights, for example, regular, semibold, bold and black. Such font families contained one or two variations in width (e.g., condensed and expanded), and specific character designs were sometimes provided for individual point sizes. Users were limited to the choices available in the font family, or they had to use artificial techniques for bolding, lightening, expanding compressing an existing design. The newer multiple master typefaces enable users to select the value of the weight, width, size and style of the typefaces along a linear scale to suit their needs.
Because multiple master typefaces are generated on-the-fly, substantially less computer storage space is required than was necessary where the entire font was maintained in storage for each weight, width or design required. Moreover, multiple master typefaces made possible the technique of font substitution, as described in U.S. Pat. No. 5,185,818 assigned to the same assignee as the subject invention. These multiple master typefaces also make documents more portable because, when a document is composed in one font and then sent to a display device that does not have that font, a multiple master typeface can be used to automatically emulate a specified font with a high degree of accuracy.
The more widespread use of multiple master typefaces has created certain problems. One of them, solved by this invention, is the unintended creation of character-specific anomalies as the weight, width, style and size are selected along their respective design axes. Whereas many of the individual characters which are selected along the various design axes using linear interpolation may be artistically pleasing, others at certain weights and widths are not so pleasing.
Referring to FIG. 1, the letter "W" is a representative character of a multiple master font of characters. Only a single font property, weight is varied along a single design axis. The "W" gets bolder as the weight increases downwardly in the direction of the arrow 13. Letter 10 at the top of the page is the lightest weight character of the ten characters shown in FIG. 1. Character 11 shown at the bottom of the page is the boldest of the ten characters.
As will be understood by one skilled in the art, this illustration in FIG. 1 represents a selection of ten characters. The font could well include interpolations and extrapolations generating a myriad of additional "W's" that are not shown in FIG. 1 or, for that matter, in FIGS. 2 and 3 which will be explained later.
To the untutored eye, all the characters in FIG. 1 generally look like a letter "W". However to a font designer, at least some of these characters are not artistically pleasing. As the font gets heavier, a font designer might prefer to connect serifs 14 and 16 instead of leaving gap 15 between them. At an even heavier weight, the designer might prefer to connect serifs 17 and 19 and eliminate gap 18 between them. In addition, the slanting line 20 in character 21 overcomplicates the character, and a font designer might prefer to have this line 20 removed. Until the present invention, there was no technique available for inserting these character-specific attributes into a multiple master font design. This invention provides a way of overcoming that deficiency.